A monolithic gallium arsenide interval timer IC with integrated PLL clock synthesis having five hundred picosecond single shot resolution

A gallium arsenide (GaAs) integrated circuit for measuring single shot time intervals with 500 picosecond resolution has been designed, fabricated and tested. The circuit contains a 12 bit counter that can be extended externally and control circuitry for the detection of multiple intervals. Options such as number of intervals, minimum interval time, and timing resolution are user programmable. The circuit employs a self contained 2.0 GHz phase locked loop (PLL) clock synthesizer with less than 5 picoseconds rms jitter, and a lock time of 2.5 microseconds. The circuit is packaged in a 14 mm/sup 2/, 52 pin thermally enhanced plastic package and operates from a single +5 Volt supply. The nominal power dissipation is 2.8 Watts. The circuit is fabricated in a 0.6 micron gate length, enhancement/depletion GaAs MESFET process utilizing 4 layers of gold interconnect metalization. Inductors, capacitors and thin film resistors can be fabricated in this process, enabling integrated analog circuitry. The die size is 3.28 mm by 3.15 mm. The circuit has applications in collision avoidance sensors, laser surveying, police radar, and test.